Achievements
Complete each achievement to get the allotted gamerscore:

A working senior (20) - Unlock Goji and use him as a player character.
Back to the future (10) - Unlock all songs in the bonus menu.
Behind the mask (10) - Unlock unmasked Poison Jam.
Paint the town red (10) - Complete Chapter 3.
Public menace (10) - Make 100 civilians jump out of your way.
Remixes suck! (5) - Complete a level without collecting a Recovery Spray Can.
Rise of Monsters (10) - Unlock Poison Jam and use him as a player character.
Scrapyard bully (5) - Shove the two civilians in No.540 level before the choppers show up.
Second coat applied (10) - Complete Chapter 2.
So creative (10) - Create a graffiti in all sizes.
Tag you're it! (10) - Tag out at least one rival gang member within 30 seconds.
That's how we grind! (10) - Perform a 100+ trick combo.
Cop sucks (10) - Draw graffiti 5 times on Onishima's back.
Detached (20) - Finish the game without anyone latching onto you with your first attempt.
Dog runs too! (20) - Unlock Pots and use him as a player character.
Feel the beat (5) - Start game for the first time.
First coat applied (10) - Complete Chapter 1.
I got Soul (50) - Collect all Graffiti Souls.
I need a parachute (5) - Fall more than 20 meters off a building.
King of the street (10) - Complete all missions with any rating.
Look behind (5) - Perform a Turn Trick in game.
Love rules (10) - Unlock Love Shockers and use her as a player character.
No Eyes in the Sky (10) - Draw graffiti 5 times on Helicopters.
Noise music (10) - Unlock Noise Tank and use him as a player character.
Number one artist (20) - Use all graffiti in missions.
The gang's all here (20) - Unlock all characters.
Training wheels (10) - Complete Tutorial.
Unlock Garam (10) - Unlock Garam and use him as a player character.
We got us a crew (5) - Unlock Gum and Tab.
When you're a Jet (50) - Complete every level with Jet rating.

Cycle Through Characters Faster
Hold [R] on the character selection screen.